Cooler



0a. 14, 1941. F, OWERS 2,258,906

COOLER Filed Sept. 7, 1940 lNVE NTOR Fro/M" 7/0/1 6/15 Patented Oct. 14, 1941 UNITED STTES gram OFFICE- COOLER Frank T. Powers, Glen Cove, N. Y. 7 Application September 7, 1940, Serial No. 355,860 7 Claims. 01. 2 11 My invention relates to the art of making photo-mechanical printing plates and more particularly to a method and apparatus for cooling plates during the process of etching printing plates.

Among the objects of my invention are to provide a method and apparatus whereby plates which have been heated in the process of etching may be cooled in a minimum of time and without the direct application to them of any liquid such as water.

Other objects and advantages of the invention will appear hereinafter or may be learned by the practice of the invention by one skilled in the art to which it pertains.

In the accompanying drawing I have shown a preferred embodiment of the invention which is described in detail herein. The embodiment shown and described is subject to numerous modifications and variations without departing from the spirit of the invention as set forth herein and embodied in the appended claims.

The drawing shows, partly in elevation and partly in section, but not to scale, an apparatus embodying the features of the invention whereby it may be used in practice.

In the drawing is shown a rectangular tray l adapted to hold a quantity of cooling fluid, preferably water, with which it is filled to the level of the top of the rim 2. Surrounding the upper portion of thetray outside of the rim is a trough 3 which is relatively shallow on one side of the tray but whose bottom slopes downwardly toward the opposite side of the tray, for reasons which will hereinafter appear.

The tray l is supported by four legs 4 attached to the four corners of the tray, which legs also support a shelf or platform 5 upon which is mounted a refrigerating unit of customary design consisting of a motor 6, a compressor 1, a cooler 8, and a fan 9. On the shelf 5 is also mounted a rotary pump I0 driven by motor ll, controlled by a switch l2 conveniently mounted alongside of the tray. Within the fluid space of the tray l is a thermostatic bulb l3, which, in conjunction with the controller M, of conventional design, controls the valve in refrigerant circulating pipe Hi to maintain a predetermined optimum temperature of the fluid within the tray I. An expansion coil I1 is completely immersed in the fluid within the tray I. Stufling boxes 18 and [9 seal the refrigerant supply and return pipes to and from the coil H. An expansion valve 20 is controlled by a thermostatic bulb ant pipe IS. The surface of the liquid in the tray is covered with a thin, flexible, tough,;watereimpervious sheet of membr-aneous material 22 which rests upon the surface of the liquid and is attached on all sides to a frame 23 which is supported upon the outer rim of the trough 3. A rectangular frame 24 of metal rod rests upon the membrane 22 and tendsto hold itlightly against the top of the rim 2 of the tray. A tubular duct 25 connects the bottom of the trough 3 at its lowest point with the suction side of the pump 10 and another duct 26 connects the discharge side of the pump I!) with the tray l at or near its central portion. The tray I is surrounded'on sides and bottom by a suitable insulating material 21 held in .place'and protected by a covering 28. The liquid levelin the tray I may be maintained by the admission ofliquid through the supply pipe 29 controlled by the valve 30. Liquid in the tray I may be drained through the waste pipe 3| under control of the valve 32.

The method of operation is as follows: Before using, the refrigerating unit is placed in operation by starting the motor 6 and its operation is con- Y tinued until the liquid in the tray is lowered to the desired temperature, preferably between 45 and F. at or near which'temperature it is automatically maintained by the thermostatic and pressure controlling devices, consisting of thermostatic bulb [3, controller I4, and valve l5, above described. When the desired liquid temperature has been reached and a plate is to be cooled, the operator starts motor II by manip ulation of switch l2 which causes a circulation of liquid through pump'lll and into the tray 1-. The liquid overflows the inner rim 2 of the trough 3 slightly lifting the membranous cover 22 and flows into trough 3. By reason of the sloping bottom of trough 3 the liquid flows around the tray l to the lowest point of the trough 3 which is at the inlet of the duct 25, through which the liquid reenters the pump l0 and continues to be circulated. After circulation of the cold liquid is established, the hot plate A to be cooled is laid upon the top surface of the membrane 22 which has been cooled. by reason of its contact on its under surface with the cold liquid within the tray and which is continuously being cooled by contact therewith.

The intimate contact of the hot plate A with the continuously cooled membrane 22 quickly cools the plate to a temperature at which the operator can handle it without physical discomfort, which is as cool as is desirable for best re- 2l clamped to, or wrapped around, the refrigersults.

I am aware that many types of coolers have been devised for quickly reducing the temperature of heated plates during the process of etching, such as after burning-in hot enamel, or powdered retardants, such as dragons blood, and that both liquid coolers and air coolers have been and are in use.

Among the disadvantages of the liquid type of cooler are the facts that the liquid comes into contact with the back of the plate and must be removed completely and with considerable care before performing the next succeeding operation. Also there is the ever-present possibility of some, even a drop, of the liquid getting on the front or etched surface of the plate and doing irreparable harm thereby.

In the case of air coolers, the time element is important since it takes very much longer to cool a plate by applying thereto a blast of air than by my new method and my new apparatus, orby the previously used wet methods.

. Another advantage which results in improved quality of product and greater convenience to the workman is the total absence of liquid on his hands at any stage of his operations. This obviates the necessity for frequent drying of his hands, or if he neglects to dry them every time he handles a plate which is wet with cooling liquid, there is always the danger of getting liquid on the front of the plate.

The flexible, pliable membrane upon which the hot plate is laid adjusts itself instantly and automatically to the surface of the plate laid upon it even though the plate may be slightly bent or warped and therefore not a true plane.

The membrane, which is not tightly drawn across the top of the tray, but rather floats upon, and is buoyed up by the liquid, comes into close contact with the entire surface of the plate and is held in intimate contact therewith by the pressure of the liquid beneath it. This results in uniform cooling rate over the entire area of the plate andeliminates uneven contraction which results from uneven rate of. cooling which is inherent in certain other methods of cooling.

The cooling of a heated plate which has a, temperature in the neighborhood of 250 F. down to. a temperature at which it can be handled with comfort by the operator, requires by this method and. apparatus only a matter of about twelve to fourteen seconds.

Having described, my invention so that one sk led, in the art to which it pertains can make and use the same, I now state what I believe to be new, and novel and for which I pray that Letters Patent be granted.

1 claim:

I. The method of cooling heated photo.- mechanical printing plates which includes bringing the back of the heated plate into contact with one surface of a sheet. of thin, flexible, liquid-impervious, membranous material, the opposite surface of which is simultaneously in contact with a cooling liquid maintained at a temperature substantially below the temperature to which it is desired to cool the plate.

2. The method of cooling heated photomechanical printing plates which includes bringing the back of the heated plate into contact with one surface of a sheet of thin, flexible, liquid-impervious, membranous material, the opposite surface of which is simultaneously in contact with a cooling liquid maintained by mechanical refrigeration at a, temperature substantially below the temperature to which it is desired to cool the plate.

3. An apparatus for cooling photo-mechanical printing plates comprising, in combination, a receptacle for a cooling liquid, a cooling liquid therein, means for reducing the temperature of said cooling liquid within said receptacle and a thin, flexible, liquid-impervious cover over said receptacle in contact with the surface of the cooling liquid therein, adapted to receive and support the plate to be cooled without contact with the cooling liquid.

4. An apparatus for cooling photo-mechanical printing plates comprising, in combination, a receptacle for a cooling liquid, a cooling liquid therein, means for reducing and controlling the temperature of said cooling liquid within said receptacle in contact with the surface of the cooling liquid therein, adapted to receive and support the plate to be cooled without contact with the cooling liquid.

5. An apparatus for cooling photo-mechanical printing plates which is characterized by having a receptacle, a cooling liquid in said receptacle, a sheet of thin, flexible, liquid-impervious, membranous. material in contact. with the surface of said cooling liquid and adapted to receive and support the plate to. be cooled, mechanical refrigerating means. for cooling the liquid in the receptacle and means for circulating the cooling liquid within said receptacle.

6. An apparatus for cooling photo-mechanical printing plates which is characterized by having a receptacle, a cooling liquid in said receptacle, a sheet. of thin, flexible, liquid-impervious, membranous material in contact with the surface of said cooling liquid and adapted to receive and support the plate to be cooled, mechanical refrigerating means for cooling the liquid in the receptacle, means for controlling the temperature of the cooling liquid, and means for circulating the. cooling liquid within said receptacle.

7. An apparatus for cooling photo-mechanical printing plates characterized by having as the heat absorbing elements a. thin, flexible, liquidimpervious: membrane. adapted. to receive the plate to be cooled upon its upper surface and a body of cooling liquid in contact with the under surface of. said membrane.

FRANK T. POWERS. 

